1. Field of the Invention
This invention relates generally to the cooling of components and, more particularly, to the cooling of the electronic packages in the operating configurations.
2. Description of the Related Art
As the density of semiconductor gates or elements associated with each electronic package has increased, the solution of the problem of removal of the heat, generated within the package has become increasingly difficult. The movement of gas directly over the packages has proven inadequate to maintain the packages within acceptable temperature ranges as the density of elements in the package has increased. To improve the efficiency of the heat removal, a cooling plate or other heat sink can be placed in contact with the package. When a plurality of components must be cooled, as can, for example, occur for the circuit boards of a data processing system, the use of a cooling plate frequently causes excessive stress on the packages when an attempt is made to insure that all components are in good thermal contact with the cooling plate. When physical contact between the component to be cooled and the cooling plate cannot be assured, then a gas with thermal properties superior to air can be used by placing the component and the cooling plate in an enclosed container. The cooling gas within the container, however, can become contaminated and the superior thermal properties compromised. The problem of providing good thermal contact between the plate and the package is further complicated by the need to access the electronic packages for testing or for maintenance.
Referring now to FIG. 1a, FIG. 1b and FIG. 1c, three techniques for providing removal of heat from component packages 15, according to the related art is shown. The component package is typically coupled to a circuit board 10, i.e. by solder bumps. The apparatus in each case provides for the transfer of heat from the package to the cooling plate 11 via an intermediate element. The cooling plate can have additional cooling apparatus associated therewith such as apparatus for permitting a cooling liquid to flow through channels in the cooling plate. In FIG. 1aa spring-loaded piston 12 (with spring 18) is forced into contact with the package 15. The heat must be transferred first from the package 15 to piston 12 and then from piston 12 to the cooling plate 11. In the implementation of this apparatus, a He gas atmosphere is used to improve the thermal contact between the piston 12 and the package 15 and the piston 12 and the plate 11. Similarly, in FIG. 1b, a screw-clamped piston 13 is coupled to the cooling plate 11. In this arrangement, the screw must be adjusted during the manufacture of the component. A thermal transfer material 14 is placed between piston 13 and package 15. It will be clear that the configurations of FIGS. 1a and 1b can cause unacceptable stress to be applied to the chip.
In FIG. 1c, a spreading element 17 is coupled to the package 15 by solder material 16. The heat is transferred from the chip 15 through the solder material 16 to the spreading element 17. From the spreading element 17, the heat is transferred to the cooling plate 11. To obtain a low thermal resistance, a gas (H.sub.2) is needed to improve the thermal coupling between spreader 17 and cooling plate 11. In addition, the apparatus of FIG. 1c and the apparatus of FIG. 1b do not permit the convenient disassembly and reassembly, there being no convenient method to determine when a good thermal contact is established.
Each of these heat transfer devices described above requires a substance to improve the thermal coupling. The presence of these substances complicates the manufacture and repair of the packages and related circuits.
Referring next to FIG. 2, an apparatus for providing thermal coupling between a cooling plate 11 and a package 15 is shown. The thermal coupling apparatus includes a holder 21 for engaging a plurality of T-shaped elements 25. The holder 21 engages a spring element 26. The spring element 26 engages a structure 11a of the cooling plate. The spring element forces the T-shaped elements against the package 15. The T-shaped structures are positioned to interleave with structures 11b of the cooling plate. A major limitation of this apparatus is the effectiveness of the thermal contact between the T-shaped elements 25 and the package 15. In addition, this configuration suffers from a lack of flexibility in that the structures 11a and the structures 11b must be fabricated in the cooling plate 11 when the position of the chip has been defined.
A need has therefore been felt for apparatus and method for providing for the removal of heat from a semiconductor element that provides a good thermal coupling and can be conveniently disassembled and reassembled.